Impact of immediate loading on early bone healing at two-piece implants placed in fresh extraction sockets: an experimental study in the beagle dog

Immediate one-piece zirconia implants with/without xenograft in the buccal gap: A 6-month pre-clinical study

OBJECTIVE

To histologically evaluate healing following grafting a xenogenous bone substitute in the buccal gap around the immediately placed one-piece zirconia implant.

MATERIALS AND METHODS

The third and fourth premolars (PM3 and PM4) in both quadrants of the mandible of nine Mongrel Hound dogs were used for this experiment. They have been removed, and the recipient sites were prepared. The implants were placed in a lingual position in the socket. In one side of the jaw, the gap between the implant and the socket walls was grafted (test) while no grafting was performed in the contralateral side (control), randomly selected. After 6 months of healing, biopsies were obtained and prepared for histological analysis. Vertical and horizontal measures were recorded in buccal and lingual surface.

RESULTS

The hard tissue was in a coronal position on the test side compared with the control side. The bone thickness around ZLA (zirconia large-grit sandblasted and acid-etched surface) level was larger on the test side. On the test side, the first bone-implant contact and bone crest, at the buccal aspect, were more coronal to ZLA in PM4 while in PM3 the same happened with the bone crest. The width of the buccal bone wall was larger in PM4 than in PM3 at the ZLA level and 1 mm apical to ZLA.

CONCLUSION

The placement of a xenograft in the gap between 1-piece zirconia implant and the buccal wall in dogs modified the process of hard tissue healing, providing additional amount of hard tissue.

Autogenous bone ring for vertical bone augmentation procedure with simultaneous implant placement: A systematic review of histologic and histomorphometric outcomes in animal studies

STATEMENT OF PROBLEM

The performance of the autogenous bone ring (ABR) technique used for the vertical bone augmentation procedure has not yet been determined.

PURPOSE

The purpose of this systematic review was to investigate whether the ABR technique for the vertical bone augmentation procedure with simultaneous implant placement enhances the histologic and histomorphometric outcomes in surgically created bone defects in animal models.

MATERIAL AND METHODS

An electronic search of 3 databases, Medline/PubMed, Science Direct, Lilacs, and a manual search of a reference list of relevant studies were performed. Only animal studies regarding vertical bone augmentation by using the ABR technique with simultaneous implant placement in surgically created bone defects were included in the review. The SYstematic Review Center for Laboratory Animal Experimentation tool was used to determine the risk of bias assessment, and the quality of included studies was assessed by using the Animal Research: Reporting in Vivo Experiments guidelines.

RESULTS

Five studies were included in the qualitative analysis based on the inclusion and exclusion criteria. One study comparing the ABR technique with the bovine and biphasic ring reported a high percentage of bone area and bone implant contact of the ABR at 5 weeks of osseointegration. Similar histologic findings were reported in another study at 4 months of healing, but contrasting data were reported at 8 months. Another study reported an increase in the percentage of bone area and bone implant contact of the ABR technique from 3 months to 6 months of osseointegration. Two studies reported an increase in the percentage of bone area, and 1 study reported a decrease in the mean of bone implant contact, both with simultaneous and staged implant procedures.

CONCLUSION

Based on the limited available studies, the use of the ABR technique for the vertical bone augmentation procedure with simultaneous implant placement presented optimal histologic and histomorphometric outcomes in surgically created bone defects in animal models. However, the results of the current review are not sufficiently robust to support the use of the ABR technique for vertical bone augmentation in humans.

Early loading of splinted implants in posterior mandible: Three-year results of a prospective multicenter study

OBJECTIVE

To evaluate the clinical outcomes of an early loading protocol of splinted implants with a fluoride-modified nanostructure surface and a tapered apex design for the therapy of posterior partial edentulism of mandible.

MATERIALS AND METHODS

One hundred and seven implants were placed in the mandible of 45 subjects at three centres in China. A minimum of two and a maximum of three implants were placed in an edentulous region using a one-stage protocol. Each subject received a screw-retained, splinted and fixed permanent prosthesis 6-8 weeks after surgery. Marginal bone level (MBL) change, implant survival and soft tissue health were assessed at 6, 12, 24 and 36 months after loading. A total of 92 implants from 40 subjects were recalled and investigated in this clinical trial.

RESULTS

After three-year loading, the survival rate of implant was 100%. On a subject level, there was a mean (±SD) marginal bone gain of 0.23 ± 0.48 mm at 36-month recall and the change in MBL was statistically significant (p = .00061) compared with time of loading. On an implant level, the change in MBL was statistically significant (p = .03914, p = .01494, p = .00000) at 12, 24 and 36 months of loading compared with time of loading.

CONCLUSION

Three-year data indicate that early loading protocol of splinted implants with a fluoride-modified nanostructure surface and a tapered apex design is feasible and safe for the therapy of partial edentulism in posterior mandible, which may contribute to bone gain when the suitable occlusal load and oral hygiene maintenance are kept.

Comparison of autogenous and allograft bone rings in surgically created vertical bone defects around implants in a sheep model

OBJECTIVES

The aim of this study was to compare autogenous and allograft bone rings in surgically created vertical bone defects.

MATERIAL AND METHODS

Four male, 1-year-old sheep were used in this study. In each sheep, eight vertical bone defects 7 mm in diameter were created using trephine drill in the iliac wing. Autogenous and allograft bone rings 5 mm in height and 7 mm in diameter were used for vertical augmentation around implants. The study consisted of four groups according to the bone ring type and amount of vertical augmentation, autogenous 2 mm, allograft 2 mm, autogenous 4 mm, and allograft 4 mm. Two of the animals were sacrificed after 4 months, and the remaining two animals were sacrificed after 8 months. Undecalcified sections were prepared from harvested samples. Histological assessment and histomorphometric analysis were performed.

RESULTS

Autogenous 2 mm group showed higher values than allograft 2 mm group, and autogenous 4 mm group showed higher values than allograft 4 mm group in terms of bone area and bone-to-implant contact (BIC) after 4 months. However, allograft 2 mm group showed higher bone area and BIC values than autogenous 2 mm group after 8 months. Also, autogenous 4 mm and allograft 4 mm groups showed comparable results after 8 months. Allograft 2 mm and allograft 4 mm groups showed higher bone area and BIC values at 8 months compared with 4 months.

CONCLUSIONS

Allograft bone ring looks promising in augmentation of surgically created vertical bone defects around implants after 8 months of healing.

Immediate loading at single crowns and 2-unit bridges supported by implants installed in a healed alveolar bony ridge or immediately after tooth extraction. An experimental study in dogs

To evaluate presumptive differences in osseointegration at implants installed in healed sites or extraction sockets, supporting either crowns or bridges that were functionally loaded or left unloaded. In six dogs, the mesial roots of the first mandibular molars were treated endodontically. Bilaterally, the teeth were hemisected, and the distal roots extracted. First and second mandibular premolars were extracted as well. After 3 months, the mandibular third and fourth distal roots were extracted after endodontic treatment of the mesial roots. Four implants were installed bilaterally, two in the healed sites corresponding to the second premolar and first molar regions, and two into the extraction sockets. Cobalt-chrome single crowns were prepared and installed in the two most anterior implants, and bridges at the two most posterior implants, bilaterally. A 3-unit bridge was applied to the premolars in the upper jaw only at the loaded sites. All prostheses had a flat occlusal surface and contacts in centric occlusion only at the loaded sites. Three months later, biopsies were retrieved for histological analysis. Higher levels of osseointegration and bone density were observed at the unloaded sites, both at implants installed in healed and post-extraction sites. However, only at implants installed in the post-extraction sites and supporting single crowns, the difference in bone-to-Implant contact was statistically significant. In implant installation immediately following extraction or delayed after three months, osseointegration and bone density were not affected by occlusal contact schemes.

Immediate and delayed loading of fixed dental prostheses supported by single or two splinted implants: A histomorphometric study in dogs

To evaluate presumptive differences in osseointegration at implants supporting crowns that are physiologically loaded either immediately or 3 months after installation. All premolars and first molars were extracted bilaterally in six dogs. After 3 months of healing, three implants were installed on the premolar region and two in the molar region in one side of the mandible. Likewise, after another 3 months, five implants were installed in the contralateral side, and impressions were taken bilaterally. Within 48 hours, two single crowns were screwed bilaterally onto two implants in the premolar region, and two splinted crowns reproducing the shape of the first molar were screwed bilaterally onto the implants in the molar region. The mesial implants were used as no-loaded controls. Sacrifices were performed after 3 months, and histological analyses were performed. At the premolar sites, mineralised bone-to-implant contact (MBIC%) was 78.0 ± 4.0% and 70.9 ± 7.9% at the delayed and immediately loaded sites, respectively. This difference was statistically significant. At the control implants, MBIC% was 61.4 ± 14.7% and 63.1 ± 13.1% at the delayed and the immediately loaded sites, respectively. At the molar sites, MBIC% was 79.2 ± 10.9% and 61.1 ± 10.3% at the delayed and immediately loaded sites, respectively. Applying a delayed loading to fixed dental prostheses supported by single or two splinted implants yielded higher proportions of bone-to-implant contact (osseointegration) compared to immediately loaded implants. Moreover, both types of loading protocols yielded a higher rate of osseointegration compared to unloaded implant sites after 3 months following implant installation.

Consecutive Case Series of Healed Single-Molar Sites Immediately Restored with Wide-Diameter Implants: A 1-Year Evaluation

Introduction. To evaluate outcomes of wide-diameter (6 mm) implants immediately provisionalized with cement-retained single crowns in posterior molar sites. Materials and Methods. Forty-eight consecutive patients received a total of 53 moderately rough-surface, 6 mm diameter implants in healed sites. All implants were immediately provisionalized with a cement-retained provisional crown. Final prosthesis with cement-retained porcelain fused to metal crowns was delivered 3–6 months later. Patients were followed up for 1 year. Outcome measures were implant failures and success rate, complications, marginal bone levels, bone level changes, papilla index, bleeding on probing, and inflammation. Results. One patient was lost to follow-up. At one year, the implant survival and success rate were 98.1%. The mean marginal bone loss after 1 year was −0.17 ± 1.84 mm. Ideal papilla score was recorded at 83.8% of the sites. More than 95.6% of the sites showed no bleeding or inflammation. No procedure-related or device-related adverse events were reported. Conclusion. Wide-diameter (6 mm) implants can safely and successfully replace single posterior molars. Longer follow-up studies are necessary to evaluate the long-term success of these implants.

Single-staged vs. two-staged implant placement in vertically deficient alveolar ridges using bone ring technique - Part 2: implant osseointegration

OBJECTIVES

The aim of this study was to evaluate the osseointegration of implants placed in a single-staged compared to two-staged procedure using bone ring technique.

MATERIAL AND METHODS

In this study were used standardized, vertical alveolar bone defects in dogs. In the test group, dental implants (Straumann BL^® , Basel, Switzerland) were inserted simultaneously with bone ring technique. As control group served implants inserted 6 months following grafting. Implants of both groups were left for an osseointegration period of 3 and 6 months. The peri-implant bone loss and bone-to-implant contact within the bone ring and native bone were analyzed morphometrically. An explorative statistical analysis was performed.

RESULTS

The peri-implant bone level remained relatively stable within groups and between groups per given time period. Most of bone apposite on the implant surface in two groups was composed of newly formed bone. A nonparametric analysis of variance (ANOVA) revealed no significant advantage for two-staged implant placement for new and total bone, except for residual bone (P = .0084). Furthermore, two groups of implants performed similarly in bone ring and in native bone throughout the observation period.

CONCLUSIONS

In terms of osseointegration, both techniques are likely equally efficient in the present defect model. The single-staged implant placement with cortical bone grafts warrants further documentation in clinical studies.

Early loading of splinted implants in the posterior mandible: a prospective multicentre case series

AIM

To evaluate the 12-months clinical and radiological outcomes with the OsseoSpeed(™) TX implant using an early loading protocol in patients with missing teeth in the posterior mandible.

MATERIAL AND METHODS

Forty-five subjects, with Kennedy class I or II edentulism in the mandible, were enrolled at three centres in China. Two or three implants were placed in one edentulous region using a one-stage procedure. Patients received a screw-retained splinted fixed permanent restoration in one edentulous region 6-8 weeks after surgery. Follow-up took place at 6 and 12 months after loading. Marginal bone level alteration, implant survival and clinical findings were assessed using descriptive statistics. The data were analysed on a patient level, implying that the mean overall implants by patient was used as the statistical unit. The data from the three centres were pooled in the statistical analyses.

RESULTS

A total of 107 implants were inserted in 45 patients. Twelve months after loading, the implant survival rate was 100%, with a mean (± std) marginal bone gain of 0.08 ± 0.411 mm and healthy soft tissue status.

CONCLUSIONS

Early loading of splinted OsseoSpeed(™) TX implants was an effective and safe treatment for partial edentulism of the posterior mandible. CLINICAL TRIAL REGISTRATION NUMBER ON CLINICALTRIALS.GOV: NCT01346683.

Differences in Healing Patterns of the Bone-Implant Interface between Immediately and Delayed-Placed Titanium Implants in Mouse Maxillae

BACKGROUND

There are no available data on the healing process at the bone-implant interface after immediate implant placement.

PURPOSE

This study aimed to establish an animal experimental model of titanium implants placed in mouse maxillae and compare the healing pattern of the bone-implant interface after immediate implant placement with that after delayed implant placement.

MATERIALS AND METHODS

Maxillary first molars (M1) from 4-week-old mice were extracted and replaced with the implant following drilling (immediate-placement group). In contrast, M1 from 2-week-old mice were extracted, followed by drilling and implantation after 4 weeks (delayed-placement group). The decalcified samples at 0-28 days after implantation were processed by immunohistochemistry, terminal deoxynucleotidyl transferase-mediated dUTP nick end labeling assay, and tartrate-resistant acid phosphatase histochemistry. The elements and bone volume of undecalcified samples were quantitatively analyzed by an electron probe microanalyzer.

RESULTS

Osseointegration was completed by 28 days after the procedure in both groups. There were no differences in contact area, bone loss at the cervical area, or rate of calcification at the bone-implant interface between the two groups.

CONCLUSIONS

This study found no significant differences in the chronological healing process at the bone-implant interface between the two groups at the cellular level.

Immediate loading of implants installed in a healed alveolar bony ridge or immediately after tooth extraction: an experimental study in dogs

OBJECTIVE

To compare the sequential healing at immediately loaded implants installed in a healed alveolar bony ridge or immediately after tooth extraction.

MATERIAL AND METHODS

In the mandible of 12 dogs, the second premolars were extracted. After 3 months, the mesial roots of the third premolars were endodontically treated and the distal roots extracted. Implants were placed immediately into the extraction sockets (test) and in the second premolar region (control). Crowns were applied at the second and third maxillary premolars, and healing abutments of appropriate length were applied at both implants placed in the mandible and adapted to allow occlusal contacts with the crowns in the maxilla. The time of surgery and time of sacrifices were planned in such a way to obtain biopsies representing the healing after 1 and 2 weeks and 1 and 3 months. Ground sections were prepared for histological analyses.

RESULTS

At the control sites, a resorption of the buccal bone of 1 mm was found after 1 week and remained stable thereafter. At the test sites, the resorption was 0.4 mm at 1-week period and further loss was observed after 1 month. The height of the peri-implant soft tissue was 3.8 mm both at test and control sites. Higher values of mineralized bone-to-implant contact and bone density were seen at the controls compared with the test sites. The differences, however, were not statistically significant.

CONCLUSIONS

Different patterns of sequential early healing were found at implants installed in healed alveolar bone or in alveolar sockets immediately after tooth extractions. However, three months after implant installation, no statistically significant differences were found for the hard- and soft-tissue dimensions.

Release of bone markers in immediately loaded and nonloaded dental implants: a randomized clinical trial

The aim of this study was to compare the release of bone markers during osseointegration of immediately loaded and nonloaded implants. Forty patients who were indicated for rehabilitation with dental implants randomly received either implant and prosthesis placement within 72 hours (group IM) or implant insertion and no prosthesis placement (group NL). Peri-implant crevicular fluid was collected immediately after implant insertion and 7, 15, 30, 60, 90, and 120 days after surgery and levels of osteoprotegerin, transforming growth factors, osteocalcin, osteopontin, and parathyroid hormone were evaluated using Luminex assay. Bleeding index and peri-implantar sulcus depth were also evaluated. The data were compared using statistical tests (α = 5%). No statistical difference was found regarding demographic and clinical parameters (p > .05). Transforming growth factors, osteoprotegerin, osteopontin, and parathyroid hormone presented an earlier release peak in group IM than in NL group (p < .05). Osteocalcin achieved higher levels in group IM versus group NL between 7 and 30 days of evaluation (p < .05). It may be concluded that earlier loading positively modulates bone mediators release around immediately loaded implants when compared with nonloaded dental implants.